In vitro digestion and stability under environmental stresses of ovotransferrin nanofibrils

The objectives of this study were to investigate in vitro digestion and stability under environmental stresses of ovotransferrin (OVT) nanofibrils. Gastrointestinal digestion of OVT nanofibrils was characterized by thioflavin T (ThT) fluorescence and atomic force microscopy (AFM). Most of OVT nanofibrils were disrupted during gastrointestinal digestion, and some OVT nanofibrils showed resistance to proteolytic digestion in vitro. Long-term storage stability of OVT nanofibrils over a wide pH range was studied at room temperature, and storage stability of beta-lactoglobulin (BLG) nanofibrils as function of pH was also studied. AFM data showed that these protein nanofibrils were stable at pHs below isoelectric point, but they were unstable at pHs above isoelectric point. It was worthwhile to note that this was the first study that relationships between long-term storage stability and zeta potential of food protein nanofibrils were clarified, which could advance understandings about long-term preservation of food protein nanofibrils. Negligible decrease in ThT fluorescence revealed that OVT nanofibrils suffered little loss of fibrillar structures after frozen storage-lyophilization-rehydration. AFM data demonstrated that OVT nanofibrils were fractured into short and curly fibrils after high-speed shearing, and ThT fluorescence measurement showed that few fibrillar structures were destroyed during shear treatment, indicating that high-speed shearing was a reliable and cost-effective strategy to tailor OVT nanofibrils for specific needs. Hopefully, this study could provide new insight about in vitro digestion and stability under environmental stresses of protein nanofibrils.